This removes tripleo-build-containers-jobs as this only contains
centos-7 jobs [1] and they are being removed with [2].
[1] 15761b77d9/zuul.d/build-containers.yaml (L119-L127)
[2] I70d2e5dbe995bc8dfe06817d6460f3f2f3732e7e
Change-Id: Idcab9a34ae7b5f20702d9a616173dd25d3894751